Batteries: Two-6V In Series, or Two-12V In Parallel ???

Let's talk real life.

It's 3 PM, your voltmeter reads 12.2v. You have minimal electrical loads, just the refrig and the CO and propane monitor. Do you recharge now, disconnect the battery for 4 hours and check the voltage (and hope the ice cream is still not melted), or wait until morning?

In 4 hours maybe the limit on generator noise will start. In the morning the voltage will be still lower. worry, worry, worry.

I guess you know my answer.